He says Harper is the common link among 13 different confidantes and advisers named in a CTV report as having knowledge of former chief of staff Nigel Wright’s plan to cut a $90,000 cheque on Duffy’s behalf.

Trudeau, meanwhile, says it’s high time Harper showed some leadership on the file.

Harper has repeatedly insisted he knew nothing of Wright’s intention to foot the bill on Duffy’s behalf until he was told about it in May.

Duffy, for his part, has told the Senate that Harper himself insisted the $90,000 in expenses be repaid, but he stopped short of directly implicating the prime minister in Wright’s repayment.

Today, the focus on the Senate scandal shifts to Sen. Pamela Wallin, who’s expected to defend herself against a motion that she be suspended without pay for her disallowed travel expenses.